1. Technical Field
This invention relates to a lighting apparatus having a control unit providing a plurality of display units, which are lighting units, with lighting information such as image data, and the display units driving light emitting elements based on the lighting information provided by the control unit, and a communication method thereof.
2. Description of Related Art
Recently, high performance red, green and blue LEDs (hereafter also called light emitting diodes), which can emit in high brightness, have been developed, so that full-color LED displaying has been achieved. Among large size display apparatuses, LED display apparatuses, which have advantages such as high brightness, long-life, lightweight and so on, have become popular quickly. Furthermore, its uses become diversified, so that a system that can adapt flexibly to various applications such as large size TVs, billboards, traffic information boards, three dimensional display apparatuses, lightings and so on, is needed.
The various screen size and pixel pitch displays having LEDs become used from outdoor use larger size displays such as for billboards to relatively small size displays in semi-indoor such as platforms depending on purpose and place. Also, vertical-horizontal ratio (aspect ratio) tends to change, for example, when high vision image such as HDTV is displayed on LED, it should comply with increased image data size and further enlargement of display panel size. In addition, when the displays selectively illuminate billboards or articles or the like, various units should be assembled with each other similarly (the display unit according to this invention includes these various applications). In highly intelligent information network, displays are also required to be compatible for connection with communication infrastructure to be remote-controlled for display or maintenance or the like.
For example there is one of the displays, which is LED display having a plurality of LED units assembled in matrix corresponding to display size or aspect ratio of vertical-horizontal ratio, or the like, works as modularized LED units disposing 16×16 dot of LEDs in matrix. An exemplary LED display 801 is shown in FIG. 17. Plural distributors 804 connected with a controller 803 are disposed so as to correspond to each of the columns of LED units 802 to provide LED units 802 with image data for display and various control signals.
The controller 803 generates a control signal 820, for example a synchronizing clock for image data, a horizontal synchronizing signal, a vertical synchronizing signal, a blank signal, a gradation reference signal and a latch signal of the image data and so on, and provides each of the LED units 802 with the control signal 820 via the distributors 804. The full-color image data 810 for displaying, which are transmitted from the distributors 804 to each of the LED units 802, are required to have image data of at least each color of RGB (red, green, blue). Bit width of the image data is determined based on resolution range of gradation.
For example, in case each of the colors is displayed in 256 gradation range, an image data bus needs 8 bit width for each of three colors. These image data are provided for LED units 802 with time-sharing in the number represented by (number of the LED unit)×(number of the displaying dots). The image data 810 are provided with bit shift in shift resister 805 of each the LED units 802. When a predetermined number of the data are provided, the data are latched then captured as the image data 810 for displaying, and thus the image data can be displayed.
However, in such LED display apparatuses, the image data 810 for displaying is transferred between the controller 803, the distributors 804, and the LED units 802 via parallel bus which is a signal interface, and synchronizing clock which synchronizes with the image data, and the various control signals 820 are supplied. Because of this, the more the LED display apparatuses get high definition or larger sized display, the more signal lines are required. Especially, these days the display screen size tends to be enlarged and the number of the LED units be increased, and these increased and elongated signal lines may cause problems such as deformation and influence to noise of pulse width of the gradation signal and the synchronizing clock.
Also, to be ready for HDTV specifications, the aspect ratio of the screen might be changed and more LED units to be connected are therefore needed. This results in higher transferring speed of the image data. Increasing the number of connection of the LED units causes deformation of the pulse of each of the signals, especially input and output timing with the image data and synchronizing the clock gets more difficult.
Further, the requirement level for displaying image quality of the LED display apparatuses is getting higher and higher year by year, as well as downsizing LED, thus further development of an LED display technology which can show high definition has become urgent. To achieve high image definition, resolution of gradation must be increased. Specifically, the data bus specification must be changed, for example, image data bus width for display should be changed from the conventional 8 bit to 10 bit. In addition, to achieve high definition, LED size should be smaller so the dot pitch width is narrower. If dot pitch width got smaller, the LED unit size would be smaller proportionately. Consequently content ratio of mounted articles such as connectors tends to be higher because of increased image data bus width.
Furthermore, conventional LED display apparatuses could not communicate in common communication way among various LED display apparatuses which have different number of pixels per unit or display gradation.
To solve these problems, we suggested an LED display apparatus, which drives LED units by transferring data formatted in ATM (Asynchronous transfer Mode) packet form added with identifying information assigned to each of the LED units, disclosed in Japanese Laid-Open Publication TOKU-KAI-HEI-126047 (1999). Also, we suggested an LED display apparatus having automatic ID assigning means adding unique identifying information of each of LED display units after connection between the LED units completed to simplify setting among the LED units, disclosed in Japanese Laid-Open Publication TOKU-KAI-2000-221934 (2000).
However, considering more high definition, and more complicated combination of the LED units or high flexible design, there are not enough, and further improvement is needed.
It is an object of the present invention to provide a lighting apparatus, communication method, a display unit, a communication circuit and a terminal adaptor thereof, which is flexible enough to be capable of various applications.